CAPACITIVE LEVEL METER Russian patent published in 1995 - IPC

FIELD: instrument engineering. SUBSTANCE: detector signal converter amplifies capacitive component and suppresses active component of detector current. Capacitive level meter has detector 1 which is connected with converter 2 through communication line 3. Detector 1 is disposed inside the vessel filled with liquid under control and has two tubular electrodes 6 and 7 and two diodes 8 and 9. Diode 8 is connected with internal electrode 7 by the cathode, and electrode 9 is connected with its anode with the electrode. External electrode 6 of detector 1 and case of the vessel are connected with common wire. Converter 2 has triangular periodic signals converter 12, two decoupling circuits. Each circuit of the converter has buffer amplifier 13(14), isolation capacitor 15(16) and load resistor 17(18), and operational amplifier 19. Resistor 20 and capacitor 21 are brought into feedback circuit of the amplifier, as well as inverter 22, scale resistors 23 and 24. Resistances of the resistor are equal one to the other and are equal to the resistance of input resistor 25 of inverter 22. EFFECT: improved precision of measurement. 4 dwg